Icicles by Lisa Densmore
Location: Avalanche Pass, Adirondack Park, New York
Now that the fake icicles adorning houses for the holidays have been put away until next year, I noticed the real icicles are starting to get rather sizeably. This clump of icy stilettos formed on a small ledge of rock above the trail into Avalanche Lake, one of my favorite backcountry ski routes in the Adirondack Park. I’ve admired these glassy spears on any number of overhangs throughout the United States where temperatures regularly drop below freezing during the winter.
Icicles remind me of stalactites inside caves. Both are shaped like a carrot and form by dripping liquid, but they are different. Icicles are made of water that refreezes as it drips. They grow bigger as water continues to dribble down the same spot. Stalactites are made of minerals left behind when water evaporates.
Though icicles are frozen spikes of water, heat is an important part of their formation process. Sunlight or some other heat source such as a warm building melts ice or snow causing it to drip. As the running water moves away from the heat source and cools, it refreezes. This refreezing process also gives off heat at the molecular level which travels up the icicle. As the heat rises, it insulates the icicle. The insulation is thinner at the bottom and thicker at the top causing the tip to grow quickly and the top more slowly, resulting in an icicle’s elongated shape.
Too bad this heat layer is indiscernible to my cold fingers on a subzero day, though I didn’t dally too long under these wintery daggers with my gloves off. I’m always a little nervous under icicles. They often break off due to their own weight and these looked hefty enough to hurt, especially from below.
